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Working with Applications
MemVerge provides additional instructions for some popular applications supported by Memory Machine, either to assist with complex setup or to support additional functionality.
Working with Hazelcast Clusters
Using MemVerge Memory Machine, you can manage the hosts of a Hazelcast cluster, capture snapshots of the cluster, and restore snapshotted clusters.
Restoring a Cluster Snapshot
Use the mvmcli cluster snaprestore command to capture a snapshot of the cluster state.

Overview and Installation
Getting started with MemVerge Memory Machine requires that you understand some background information about how persistent memory works. You can then install Memory Machine on a server and begin monitoring memory usage and capturing application snapshots.
Using the Memory Machine Management Center
Memory Machine Management Center (M3C) is a web UI application available on the host that is running the Memory Machine Management Service. You can view system resources and performance metrics; create and restore snapshots; schedule jobs; and more in M3C.
Using the Command Line Interface
You can administer and use MemVerge Memory Machine using the Command Line Interface (CLI) on any installed host.
Working with Applications
MemVerge provides additional instructions for some popular applications supported by Memory Machine, either to assist with complex setup or to support additional functionality.
- Working with Hazelcast Clusters
  Using MemVerge Memory Machine, you can manage the hosts of a Hazelcast cluster, capture snapshots of the cluster, and restore snapshotted clusters.
  - Preparing Memory Machine to Work with Hazelcast
    To prepare for taking snapshots of the Hazelcast cluster, install Memory Machine and provide the Hazelcast credentials to all hosts in the cluster.
  - Preparing Hazelcast to Work with Memory Machine
    To prepare Hazelcast to work with Memory Machine Cluster Snapshot you must configure Hazelcast on each host; create a user that belongs to the Memory Machine mvmm group; run Hazelcast on each host in Active state as a background process; and register the Hazelcast cluster with Memory Machine.
  - Capturing a Cluster Snapshot
    After configuring Memory Machine and Hazelcast, use the mvmcli cluster snapshot command to capture a snapshot of the cluster state.
  - Restoring a Cluster Snapshot
    Use the mvmcli cluster snaprestore command to capture a snapshot of the cluster state.
  - Deleting Cluster Snapshots
    Delete a cluster snapshot using the mvmcli cluster snapdelete command on the Primary Coordinator host.
  - Working with Clusters in Memory Machine Management Center
    Create and capture and restore snapshots of a Hazelcast cluster from the command line or Memory Machine Management Center.
  - Troubleshooting Hazelcast Cluster Snapshot
- Working with KVM in Memory Machine
  Running KVMs in Memory Machine requires extra setup and configuration.
- Working with Redis in Memory Machine
All Documentation
Links to all technical documentation for MemVerge Memory Machine including previous releases.

Restoring a Cluster Snapshot

Use the mvmcli cluster snaprestore command to capture a snapshot of the cluster state.

Before you begin

Shut down all of the cluster members. The restore process will fail if any cluster member's address and port are occupied by a process.

Procedure

Use the mvmcli cluster list command to display all the available cluster snapshots. For example, using the cluster for which a snapshot was captured in Capturing a Cluster Snapshot:

# mvmcli cluster list
Name                Profile     Cluster Contact Member   Create Time
---------------------------------------------------------------------------------
---------------------
hz-cluster-1        hazelcast   10.0.0.63:5701           Tue Dec  1 16:09:15 2020
Snapshots:               Status         Label               Create Time
                                        hz1-snap01          Tue Dec  1 16:32:05 2020
                                        hz1-snap02          Tue Dec  1 16:58:52 2020
#

Using the label chosen from the displayed cluster snapshots, restore the cluster snapshot with the mvmcli cluster snaprestore command.

Important: Always restore cluster snapshots with the mvmcli cluster snaprestore command. Do not try to restore individual snapshots from a cluster snapshot using mvmcli snapshot restore. The mvmcli snapshot restore command will start simultaneous instances in the same application namespace, which can result in a process crash or data corruption.

Warning:
Replacing a certificate will cause restore of existing cluster snapshots to fail.

If you create a Hazelcast cluster with TLS using a certificate, then replace the certificate in the Hazelcast cluster and on the coordinators, any snapshots you take before replacing the certificate cannot be restored. This is expected behavior; a snapshot should be restored only under the certificate it was captured with.

For example:
```
# mvmcli cluster snaprestore --name=hz-cluster-1 --label=hz1-snap01
#
```
Optional: To verify that all Hazelcast members in the cluster were restored, use the mvmcli snapshot list command on each Hazelcast host.